Mixed-ringing party-line telephone system



R. W. HUTTON Feb. 17, 1959 2,874,223

` MIxED-RINGING PARTY-LINE TELEPHONE: SYSTEM Filed Aug. 27, 1955 4Sheets-Sheet 2 05.5725 v oo :Brig

mu mm OO.

MIXED-RINGING PARTY-LINE TELEPHONE SYSTEM Filed Aug. 27, 1953 Feb. 17,1959 R. w. HUTTON 4 Sheets-Sheet .'5

NO D KKKKKRKA O W ooMBml-:o cone AND HARMONIC RINGING FG. 4 oouPLERsoo-LB Feb.17,1959 l R,W.HUTTON 2,874,223

MXED-RINGING PARTY-LINE TELEPHONE SYSTEM Filed Aug. 27, 1955 4Sheets-Sheet 4 vto the station called, as

of the code-ringing block coupler 2200 of the noted Bellamy et al.application are given similar reference characters whenever suchassignment is possible. Of the impulse counting devices SE to SR of thenoted code ringing clock coupler 2200, only stations register SR isshown. Relay 2260 is an added relay which has no counterpart in coupler2200, butfkelays 2201 to 2215 are similar respectively to the relays ofthe corresponding coderinging coupler except for contacts added tocertain relays to control the circuits of the added relay.

Added relay 2260 is a code relay which is operated to supplycode-ringing current in accordance with the code assigned to the calledstation in lieu of the normal harmonic ringing current which wouldnormally be placed on the called line. Common wires CC, RR, and ST-l toST-10 are common wires similar to those employed in code-ringing coupler2200. Code ring wire CR and wires INT-GRD l to INT-GRD 10 are newlyadded wires.

The seizure of the block coupler SOD-LA, the receipt of the digit pulsesof the directory number, the calling-in of the block controller, thechain seizure and guarding, the digit setting of the block translatorand the testing and seizure of the called line is as described in thenoted Bellamy et al. application.

II. DETAILED DESCRIPTION A detail description 4of the first embodimentof the invention will now be given.

IIA. Harmonic ringing coupler operation Block coupler 500-LA and itsassociated common ringing apparatus provide for accommodating tenharmonic ringing stations, either bridged or divided ringing, on anyparty line by (l) employing a one-ring code and a two-ring code for eachof live frequencies of ringing current, and by (2) ringing over one lineWire or the other according shown in the harmonic-ringing chart of thenoted Bellamy et al. application.

As noted in the above application, in order to provide i theabove-mentioned party-line ringing service, the ten interruptedgenerator leads INT-GEN tor9 are controlled by the usual common ringingapparatus, in that the station generator leads numbers 0, 1, 2, 3, and 4have respective frequencies 1 to 5 applied thereto once each ringingcycle and in that generator leads numbers 5 to 9 have respectivefrequencies 1 to 5 applied thereto twice during each ringing cycle.

As will be described hereinafter, if the desired station called is oneon a code-ringing line, ground potential will appear on the code-ringingwire CR extending between coupler 500-LA and the modied block translatorshown I in Fig. 3. However, assuming that the called station is one o na harmonic-ringing line, no'ground is forthcoming over the CR wire andthe coupler functions as a harmonic-ringing coupler.

Responsive to the operation of terminating chain relay 2212, contacts 9ground conductor 2224. Ground is thereby extended through the selectedcontacts of station register SE and thence to the corresponding contactsof harmonic ringing relay 2215 (transfer relay of the block coupler ofthe noted Bellamy and Bowser application) to the selected one of thestations wires ST-1 to ST-10 extending to the modied block translatorover conductors in cable 223A.

As described in the noted Bellamy et al. application, if stations digits0 to 4 have been dialed, no ground appears on the ring-reverse wire RR.However, if the digit information received over the stations wires showthat any station digit 5 to 9 has been dialed, ground appears on thering-reverse wire RR and is extended through make contacts 11 of chainrelay 2212 to the batteryconnectedjwinding of ring-reverse relay 2206,which operates. When it is thus operated, ring-reverse relay 2206reverses the ringingleads at its contacts 1 and 2 and at its contacts 3prepares to lock itself to ground,

A i 4 Y through contacts on the switching and ring-cutoff relays, relays2210 and 2207.

As described in the noted Boyer application, the block translator uponreceiving the extended digit information transmits a suitably translatedversion of the digits to the line controller of the frame terminatingthe called line, whereupon the line controller and the block controllerdetermine the busy or idle condition of such line.

If the called line is busy, the busy relay (not shown) is operated andbusy tone is returned to the calling line as described in the Bellamy atal. application.

If the called line is idle, and an idle path can be matched thereto, theblock controller (not shown) and switch wire SW of the block couplermechanically closes a connection to the called line. Upon the connectionbeing extended to the called line, contacts'on the primary switches 103associated with the block coupler returns ground over the hold pilotwire HP which thereupon operates switching relay 2210 as described inthe Bellamy et al. application.

Upon. operating, switching relay 2210 restores the chain relay and freesthe terminating chain and the common control apparatus; contacts'7complete the locking circuit of ring-reverse relay 2206 if it isoperated; contacts 8 extend ground to the battery-connected winding ofharmonic-ringing relay 2215; contacts 2 and 3 close the ringing circuitto the called line; and the remaining contacts not shown perform theirrespective functions. l

Upon operating, harmonic-ringing relay 2215' transfers the output leadsof the stations register SR from the stations leads ST extending to theblock translator to the ten interrupter generator leads INT-GEN 0 toINT-'- GEN 9.

The ringing circuit for the called station on a harmonic ringing line isfrom the selected one of the interruptor generator leads INT-GEN 0 toINT-GEN 9, the associated break contacts of code-ring relay 2260, makecontacts of harmonic-ringing relay 2215, the selected contacts ofstations register SR, conductor 2285 through contacts 1 of code ringrelay 2260, the winding of ring-cutoff relay 2207, make contacts 3 ofswitching relay 2210, and

break contacts l of relay 2253 from whence it passes to the tipconductor T of the called line (if stations digit 0 to 4 has been dialedand ring-reverse relay 2206 is not operated) through break contacts 2 ofrelays 2206 and 2207 or to the ring conductor R of the called line (ifthe stations digit 5 to 9 has been dialed and ring-reverse relay 2206 isconsequently operated throughrmake contacts 2 of ring-reverse relay 2206and break contacts 3 of ringcutoff relay 2207.

A return path to ground for the transmitted ringing current is provided(1) over the ring conductor R (when ring-reverse relay 2206 is notoperated) through break contacts 3 and l of relays 2207 and 2206, andmake contacts 2 of switching relay 2210 to generator-ground conductorGEN-GRD, or 2) over the tip conductor T (when ring-reverse relay 2206 isoperated) through break contacts 2 of relay 2207 and through makecontacts 1 of ring-reverse relay 2206 to conductor GEN-GRD.

Ringcutol relay 2207, whose line winding is included in the ringingcircuit does not operate before the call is answered for each ringer onthe called line (not shown) has the usual condenser in series therewithto block direct-current ow and because the shading collar sur.- roundingthe armature end of the core of relay 2207 keeps it from responding tothe alternating ringing current.

As pointed out in the noted Bellamy et al. application, ring-cutoffrelay 2207 may be operated by directcurrent flow during the applicationof ringing current as the ringing current is in series with the exchangebattery, and during the silent period as ybattery alone is supplied toeach of the generator leads rather than generator current in series withthe exchange battery.

When the call is answered at the called station, the closure of Atheusual talking bridge across the called line causes current to flowthereoner from the generator lead in use, operating ring-cuto relay 2207through its .line winding sufciently to close its preliminaryfmakecontacts `4. a These contacts .close a local self-locking circuit andoperate `relay 2201 fully. At its contacts 2 and 3, relay 2207 kopens.the ringing circuit and completes the talking circuit, and'rrestoresrelay 2206 and relay 2215 as pointed out in the noted Bellamy et al.application.

The :answer supervision, the completion of the talking circuit .and'.the consequent clearout after conversation is `asdescr-ibed in'rthenoted :Bellamy et al. application.

Block coupler 50G-LA permits reverting calls vto vbe made as none -ofthe added relays alect reverting call operation.

IIB. Code-ringing coupler operation When the called station is one on acode-ringing line, coupler 50G-LA responds to control frorn the modifiedtranslator ofthe Boyerapp'lication'to condition the block coupler #tochange over Ifrom -a harmonicring'ing coupler to fafcoiie-ringingcoupler. This operation is 'as follows:

'The'combined code and kharmonicring'ing'block coupler 500-LA inaddition to providing lthe hereinbefore described harominc-r'ingingservice, provides ten-station and twenty-station code-ringing service.Relay 2251 4is 4a `code-'controlrelay operable over wire CC from theassociated translator -to cause `the pickup -relay 2252 to Vbe-operatedin an earliervportion of the code-ringing cyclelto therebycausea-'preliminaryring to be transmitted when the stationbeing-clled is oneof the second vstations en a twenty-station line, code relay 2253-is-oper-atedto apply ringing current-in faceordance withthe codeassigned to lthe called station, and code-ring `rrelay 2260 operateswhen l:the called station is` on `a Ycoderinging line to ftrans- Afeithei-stationawireslfroni theinterruptetl generator leads to Atheinterrupted :ground leads vfor code ringing.

Common wires"L,1PU-1,PU%2, CC, -andRR are cornmon wiresfemployed 'for`block coupler 500-LA infaddi- 'tion to the other Lwires not shown butset 1forth in the Vnoted-Bellamy-et al. application.

HBL yTen-.station code-ringing operation- When blockcoupler 500-.LAVisemployed to `call a coderingingline having `=notrnore `thanten stationsthereon, the common code control conductor CC incoming from theassociatedn block translator is not grounded, wherefore code controlrelay VY225.1 remains operated.

. `Responsive .to theoperation of Ychain relay landfthelconsequ-ent.grounding of conductor 2224, Vground appear- ,on ftheselected one of the stations -wires ST-l to ,ST-,10. ,is rextended `to`blockA translator 1800 over corresponding conductors in cable 223A andlthe translator responds `as hereinbefore noted to l.direct the call .tothe ^`called line .and tov transmit the proper identifying signalnotifyingthe block coupler whether the station/,called is:one,onlatenfstation,line or one on. a twenty-station line.

,llsoftranslator 1800 transmits information; over ,the code ring-wireVCR notifying the block. coupler .whether the .calledstation is .on acode-ringing line or not.

`Responsive tothe lgrounding-of the code wire CR when ,thesca'lledstation is on a codefringingline, `ground is extended through makecontacts 13 of chainrelay` 2212 .to the battery-connected winding ofcodefringrelay 2260. Code-ring 'relay.,2260operates and prepares to lockoperlated through its makecontacts l4.`

I'Responsive to the common control apparatus -v ,testing 'the `calledlineand ftinding it` idleit extends the` calling connection ashereiribefore noted. Upon the consequent return of; ground on hold-pilotwire- HP, -switching relay 12210 is *operated and chain relay 2212v isrestored. Con- @Qt f8 ,of theswitching relayv22`1'0 ylock relay A2260operated andapply ground potential to the battery-conringing relay,f2215, causing "it'to operato. J'Contacts 1 and2 ot relay 2260disconnect .335mm Wire Z224' and connect it t0 better-y .potentialthrough -resistor 2286.

At the time the ringing oper-ation is ready to commence, blockcouplerSUO-LA has been .seized over its incoming conductors T, R, andSfandoperations Yhave occurred he'reinbefore described for coupler 500-LA tocause the outgoing conductors T, R, and S to be extended .through aprimary switch to the calledline. At that time, switching relay 2210Aand code-ring relay 2260 are operated. Responsive to such operation -ofswitchingrelay 2210, harmonic-ring relay 2215 operates and locks.Contacts 2 and 3 of switching relay 2210 extend generator groundGEN-.GRD to contacts l of ring-reverse relay 2206 and extend thebattery-connected trip winding of relay 2207 V(from the :battery throughcurrent-limiting resistor 2286) through break contacts'l of code relay2253 to` contacts .2Y ofringreverseirelay 2206. Fromcontacts l and2 ofrelay .-2206, ythese noted conductors are extended through breakcontacts Zand 3 of ring-cutol relay 2207 to `conductors T fand `R in theoutgoing group yand consequently to the called line'.

Contacts on relay 2215 and 2260 transfer the output -wires of thestations register "SR from the stations-.leads ST-l *to ST0 nto thecommon code wires Code-0 'to Code-a9.

Wires Code-0 Ato Code-9 are controlled by `the Vcode ringing Vapparatus(not shown) which controls the wires PIJ-e1 4and. PU2 which areassociated with relays 2251 and 2252. Wire 2224 is connected to one oranother of the gwires :Code-0 to Code-9 through make contacts of4harmonic-ring relay 2215 and code-ring relay 2260 depending upon the[setting which is vimparted to the .stations .register SR.

With code -control relay 2251 restored as assumed, (the called line is aten-party line) the second `pickup wire *PU-2 is connected throughcontacts l of relay 2251, 1break contacts 2 vof pickup relay 2252,.break contacts 9 of relay 2207, make contacts 9 of switching-relayft221`0 and makecontacts 13 of relay 2260, to thebattery-connected Vwinding ofpickup relay 2252. Consequently, when PU-2is next grounded, just prior .to .the `beginning of the normalVcode-sending operation of Ythe common apparatus, pickup relay2252 iisoperated thereover. Contacts 2 thereof lock the relay to locking :wire:L and disconnect pickup wire'PU-2. Contacts :l of,pickup relay 2252connect common wire 2224 of register SR'to code relay 2252. As a result,each time .acodesignal is placed on one of the wires yCode-0 to Code-9,code relay 2253 operates for the durationof the signal. At its contacts1, vrelay 2253 disconnects :the trip winding ofrelay 2207 andsubstitutesrthe com- :mon vgenerator ,wire vGEN Vover which the `commonsource of ringing current is supplied. Ringing current is'therebytransmitted to the'called line for the durationl vof 'operationof coderelay 2253. One yor more consequent 4operations of code relay 2253during the current cycleof the common ringing machine transmits ringingcurrent over the called'line in accordance vwith-the code zass'ignedtothe called station thereon. This code signal .isgrepeated as many .timesas desired, but each'time the c ommon ringing equipment reaches thesilent interval, it opens Wire L, unlocking `and restoring any voperatedpickup relay 2252, which subsequently reoperates if the call has notbeen answered-when pickup position is again reached. Y v

'Ring-reverse relayr2206 operates as described to cause ringing currentto be sent over the ring lconductorLR `(rather than the tip conductorHT) yfor the last ,ylye stations, 5 lto 9, ona teni-station linerpermitting divided ringing to be used, if desired.

When the call is answered, or soon thereafter,` code relay` 2252restores if it is then operated, the upper windingo'f rcutoff relay 2207yis .energized over- `the `called line,

through contactsZ and3 of relayr2207 andl contacts 1ntl v2 f relay 2206to ground through 'contacts V1 of code relay 2253 and make contacts 2 ofrelay 2210. At its contacts 4 relay 2207 thereupon locks its own windingto ground on conductor2219 with results, as hereinbefore described,which include the opening of the ringing circuit and the closing of thetalking circuit. Additionally, contacts 9 of relay 2207 restore pickuprelay 2252 (if then operated) thereby disconnecting code relay 2253.

The remaining operation of block Ycoupler 500-LA in clearing out is asherenbefore described in the noted Bellamy et al. application with relay2260 restoring when relay 2210 restores.

IIB2. Twenty-station code ringing operation When a twenty-station lineis called, the described normal code-ringing operation of block coupler500-LA occurs if a called station is one of the first ten stations onthe called line, that is one of the stations indexed by the sufix of thedirectory number normally assigned to the concerned line, as describedin connection with the operation of the block translator of the notedBoyer application.

When the called station is on a twenty-station line, the blocktranslator operates as described in the Boyer application to applyground potential to the common code control conductor CC. This operationoccurs while the terminating chain relay 2212 is in an operatedcondition, thereby closing a circuit through contacts 12 thereof forcode control relay 2251. Relay 2251 thereupon operates and at itscontacts 2 prepares a locking circuit which is closed in due course atcontacts 7 of switching relay 2210 to ground through contacts 8 of ringcutoff relay 2207. At its contacts 1, code control relay 2251disconnects the second pickup wire PU-2 and substitutes the first pickupwire PU-1.

When switching relay 2210 operates, as hereinbefore described, contacts9 thereof connect pickup relay 2252 through contacts 13 of relay 2260,contacts 9 of relay 2207, normally closed contacts 2 of relay 2252, andmake contacts 1 of operated relay 2251 to pickup wire PU-l. Relay 2252therefore operates to start the coderinging operation as soon as wirePU-l is next grounded.

The previously-mentioned common ringing equipment is of the well knowntype which first momentarily grounds pickup wire PU--l` and latergrounds pickup wire PU-2. In the interval between the two pickup pulses,the common ringing equipment transmitsthe preliminary code signal overwires Codeto Code-9. Having been operated over wire PU-l, pickup relay2252 is now in an operated condition when the preliminary ringing signalis transmitted by the common ringing equipment. As a result, code relay2252 receives the distinguishing preliminary signal over one of the codewires selected by the stations register SR, and transmits acorresponding preliminary ringing signal, followed by the station codeindicated by the current setting of stations register SR. Thetransmission of the preliminary ringing signal identifies the calledstation as being one in the second group of ten on the called linerather than one in the first group of ten thereon.

The remainder of the operation of block coupler 500-LA is as describedhereinbefore.

IIC. Translator code-ringing contro'l a portion of the pin terminalsection of the detectory field used in conjunction therewith. A Of theten sections of the pin-terminal section of the noted Boyer application,only the rst and the second sections 1901 and 1902 are shownfragmentarily. The first and vsecond four five-level groups of each ofthese two sections are the only ones shown, the remainder being assumedas disclosed in the Boyer application. t

The one hundred terminals in groups 1 and `2 of section 1901 correspondrespectively to registered hundreds digits 0 to 9 and tens digits 0 to 9and terminate wires, 00 to 99.

The 100 terminals in the first ten levels, comprising groups 1 and 2 ofsection 1902 are assigned respectively to registered units digits 0 to 9and terminate units wires U0 to U9.

HC1. General operation for code-ringing line detection As contrasted tocommon-numberA service, line-intercept service, and line-number-transferservice described in the noted Boyer application, code-ringing linedetection service does not affect the normal fixed translation as does theabove noted services.

The detecting operation is performed by individual code-ringing detectrelays separately assignable to desired numbers to be detected. The tendetector relays 18N1 to 18N10 are so adjusted to operate only if bothwindings are energized. For each detector relay, these windings arewired to separate detector terminals D1 and D2 from whence they may bejumpered as desired throughout the detector field.

To prepare a detector relay to detect a specific called station orcalled number, a twoconductor jumper is run from its terminal pins D1and D2 to carry the winding terminals of the detector relay to the twoterminal pins of the detector field section 1901 or 1902. If one suchterminal pin is a hundreds and tens pin in groups l and 2 of section1901 and the other a units pin in groups l or 2 of section 1902, groundwill appear on both such terminal pins only when the specific num beriscalled. The concerned detector relay then operates as both of itswindings are energized, each over Va separate wire of the noted detectorjumper.

Jumper 18N20 is one example of the noted two-wire detector jumperconnected between the hundreds and tens detect field and the unitsdetect field.

IICla. Ten-line group detection Assuming that the last ten lines in thesecond group of 100 lines are code-ringing lines, the operation of theblock translator in transmitting identifying information to the blockcoupler 500-LA to condition it to codering such lines as follows:

Assuming that the hundreds digit dialed is a 1 and the units digit is a9, as pointed out in the noted Boyer application, ground potential fromthe hundreds Yand tens register relays of block translator 1800 appearon terminal 19 in the detector field of section 1901 over thecorresponding conductor in cable group DF-l. Ground appearing onsuchterminal is extended over the jumpers D1 and D2 of two conductor jumper18N11 to the corresponding terminals D1 and D2 on the rst code-ringingdetect relay 18N1.

Relay 18N1 operates and at its contacts extend ground potential overcode-ringing wire CR to block coupler SUO-LA over conductor CR in cable223A to cause the code-ring relay 2260 thereof to operate as previouslydescribed and to cause the called station on the coderinging line to becode rung.

As previously pointed out, the code-ring relay of the 'coupler operatesand is followed shortly thereafter by the restoration of the chain relaywhich frees the eommon equipment and removes groundfrom the detectorfield.,V The removal of ground from the detector eld APCode ringing-detector-relay "lS'NZ is "shown-connected "jt'of'the 1hundreds 'and-tens '"wire- 06 of (the hundreds 'and *tens detector field,whereby-responsive, to the dialing ktif the Jf hundreds digit 'and',aitens 'digit F16, the" code-ring `'iv'iire iis' grounded"thereby:causing *all ten "lines in that group to be code ringing lines.

IIClb. Individual-line detection If it is desired to have an individualcode ringing line in place of the described ten-line group of code`ringing lines, detector jumper 18N20 is connected as illustrated todetector relay 18N10.

As shown in Fig. 3 of the drawings, the two-wire jumper 18N20 has itsdetector lterminal D1 connected to the hundreds and tens terminal pin 85and has its detector wire D2 connected to the units bus bar U5.Therefore responsive to the dialing of the hundreds digit 8, the tensdigit 5, and the units digit 5, both windings of the detect relay 18N10are energized and relay 18N10 operates and grounds the code-ring wire CRin the manner previously described.

Under such arrangement, any individual line or any group of ten lines ina group of one thousand lines may be code-ringing lines by theassignment of a coderinging detect relay to such directory numbers.

III. SECOND EMBODIMENT (Fig. 4)

Referring now to Fig. 4 of the drawings, a description of the secondembodiment of the invention will now be given. In this embodiment, thecoupler is conditioned to code-ring certain lines without the aid of thespecially modified block translator.

In block coupler 500-LB, the parts similar to those of the block couplerof Fig. 2 are given similar reference characters but in the 2300 seriesrather than the 2200 series. The impulse counting devices SE to SR ofblock coupler 500-L of the noted Bellamy et al. application are similarto those of Fig. 4 of the drawings with the exception of the initialdigit register IDR.

As noted in connection with Fig. 2, code-ring relay 2360 when operated,conditions the coupler for code ringing. Relay 2360 is an added relaywhich has no counterpart in Fig. 5 of the noted Bellamy et al.application but corresponds to the code-ringing relay 2260 of Fig. 2.Relays 2351 to 2360 and common wires CC, RR, and ST-l to ST- are similarrespectively to the relays and wires of the corresponding code ringingcoupler of Fig. 2. However, code-ring wire CR is omitted as thechange-over from harmonic ringing to code ringing is accomplishedinternally without the aid of the translator.

The seizure of block coupler 50G-LB, the receipt of the digit pulses ofthe directory number, the calling-in of the block controller, the chainseizure and guarding, the digit setting of the block translator, and thetesting and seizure of a called line is as described with reference toFig. 2. However, tween code and harmonic ringing is determined by thedialing of one or another of two initial digits assigned to the locallines of the exchange.

IIIA. Harmonic-ringing operationy When the block coupler 50G-LB isemployed to call a harmonic-ringing line, the dialing of the initialdigit 6 to index the call as a local call, as described in noted Bellamyet al. application, is followed by the dialing of the remaining digitsof the directory number. Under such assumed condition, the initial digitregister IDR operates its make contacts 6 to mark the call as a locallyterminated call and the operation of block coupler SOO-LB is asdescribed for block coupler 500-LA on a call to a station on aharmonic-ringing line.

the discrimination be- 10. jIII-B. Cae-rngngmperation YWhen the called*station is Aon accde-ringingtlinmthe initial digit'prexingthefdirectorynumberf-ofesuchfesired line and fstationfisyiarssurn'ed :to f'be'the initial .'digit irln -this embodimentthelfinitial `digitwire IDS ioffrthe muted Bellamy-etal. applicationdoes not-extendf'to ,the, initial digitfrelaysbut is changed -.to becomethe-equivalentf the code-ring wire CR of Fig. 2.

Upon dialing such initial digit, ground from the break contacts 6 andmake contacts 5 of initial digit register IDR appears on the code-ringwire CR and is extended through contacts 13 of chain relay 2312 to thebatteryconnected winding of code-ring relay 2360, in a manner similar tothe way the ground from block translator 1800 appearing on the code-ringwire CR is extended thereto.

The operation of the combined code and harmonic ringing coupler 50G-LBfrom this point forward is as described with reference to Fig. 2 ofblock coupler 50G-LA, with the removal of ground from wire CR occurringwhen the register IDR restores.

I claim:

l. In a telephone switching system, party lines of a rst ringing typeeach having stations thereon arranged to be signalled by a first type ofparty-line ringing current, party lines of a second ringing type eachhaving stations thereon arranged to be signalled by a 1second type ofparty-line ringing current, each said party line being indexed by aseparate line number, each station on any said line being indexed by aseparate station number, couplers and trunks extending respectivelythereto, means controlled from a calling line for seizing any trunk andassociated coupler, means for transmitting number signals over theseized trunk which comprise line-number signals representing the numberof any party line of either said ringing type, and further comprisestation-number signals representing the station number of the calledstation on the called line, means for recording the line number and forrecording the 'station number represented by said signals, automaticswitching apparatus, means for controlling the switching apparatus fromthe recording means to extend a connection from the seized coupler tothe called line indexed by the recorded line number, stationselectingmeans in the seized coupler and means for operating it from therecording means to select the called station on the called line indexedby the recorded station number, type-selecting means in the seizedcoupler operable to select either of said types of party-line ringingcurrent, means for operating the type-selecting means from the recordingmeans according to the recorded line number and irrespective of therecorded station number, and means in the seized coupler for applyingringing current to the called line of the type selected by thetypeselecting means to signal the called station selected by thestation-selecting means.

2. In a telephone switching system according to claim l, the saidsignals including a signal group in addition to the signal serving toindicate the called line and station thereon, the means for operatingthe type-selecting means including means responsive to the signals inlsaid additional signal group.

3. In a telephone switching system according to claim l, wherein the tworinging types of lines have respective blocks of line numbers assignedthereto, the line numbers in each block being assigned to respectivelines, signalresponsive means for indicating the line number of thecalled line and the number block which contains it, and means forplacing the type-selecting means under the control of the saidsignal-responsive means.

4. In a telephone switching system according to claim 3, saidsignal-responsive means including a translator common to all of the saidcouplers, said translator being included in the said means forcontrolling the switching apparatus to extend the connection Yfrom aseized cotipler to the called line.

.- 11 k 5. In a switching system according to claim l, two sets `ofringing leads common'- to all said couplers and means for supplyingrespective types of ringing current over said' sets, Ithe-type-selecting means including' means for selecting veither of saidsets according to the ringing type to k"which the called line belongs,and said station-selecting means including means for connecting any saidringing leadl of either selected set into circuit with the called line.

snags 12 Y References Cited in the le of this patent UNITED STATESPATENTS Howitz et al. Oct. 2, 1956

